Colour was on offer since at least Widows 98. In fact, desktop themes were a thing, with custom wallpaper, colours, icons - precisely so the computer looks less dreary. If GNUStep was impossible to theme (or if theming was hard to implement there), I'd be surprised.
Information density the one thing 1995 interfaces got right for power users. Modern applications fit 10 items per screen, and most don't bother to make this adjustable. My desktop computer or laptop could outcompute a Cray twice over, and yet I'm made to feel like I'm stripped of all that power.